Orthogonally protected carbohydrate-based scaffolds

Fluoride-Mediated Desulfonylative Intramolecular Cyclization to Fused and Bridged Bicyclic Compounds: A Complex Mechanism

We previously reported the synthesis of polysubstituted chiral oxazepanes in three steps from commercially available starting materials. The unexpected reaction of one of these 1,4-oxazepanes in the presence of TBAF provided a 4-oxa-1-azabicyclo[4.1.0]heptane core. This unusual process significantly increased the complexity of the molecular scaffold by introducing a bicyclic core. Surprisingly, the generated bicyclic structure featuring three stereocenters was a mixture of enantiomers with no other diastereomers observed. These striking experimental observations deserved further investigations. A combination of experimental and computational investigations unveiled a complex diastereoselective mechanism. Mechanistic rationale is presented for this observed rearrangement.

Carbohydrates as scaffolds in drug discovery

Drug discovery has long suffered from the difficulty of having to place pharmacophoric groups in just the right spatial arrangement to elicit the desired biological response. Although some molecule classes have been discovered that seem to be privileged structures for at least some drug-receptor interactions, there remains the challenge to design and synthesize molecules with high specific affinity to pharmacologically important targets. With their high density of stereochemical information and their relative rigidity, carbohydrates provide excellent platforms upon which to display a number of substituents in a sterically defined way, hence offering the opportunity to harness their unique features for the drug-discovery process. This review highlights the progress that has been made in the development of carbohydrate scaffolds for drug discovery.

Recent trends in the synthesis of O-glycosides of 2-amino-2-deoxysugars

The discovery of new methods for stereoselective glycoside synthesis and convergent oligosaccharide assembly has been critical for the area of glycosciences. At the heart of this account is the discussion of the approaches for stereoselective synthesis of glycosides of 2-amino-2-deoxysugars that have emerged during the past two decades. The introductory part provides general background information and describes the key features and challenges for the synthesis of this class of compounds. Subsequently, major approaches to the synthesis of 2-amino-2-deoxyglycosides are categorized and discussed. Each subsection elaborates on the introduction (or protection) of the amino functionality, synthesis of glycosyl donors by introduction of a suitable leaving group, and glycosidation. Wherever applicable, the deprotection of a temporary amino group substituent and the conversion onto the natural acetamido functionality is described. The conclusions part evaluates the current standing in the field and provides a perspective for future developments.